1. Field of the Invention
This invention relates to the false twist processing of synthetic fibers, particularly polyester and nylon fibers with fiber processing aids applied as spin-finishes subsequent to extrusion of the fibers from the spinneret.
2. Description of the Prior Art
In the production of polyester and polyamide filament, the addition of a chemical coating after extrusion from the spinneret is essential in order to process the emerging filaments into fibers. It is known to utilize, as fiber lubricant components, polyoxyethylenes and heteric polyoxyalkylenes derived from ethylene oxide and 1,2-propylene oxide derivatives of fatty acids and fatty alcohols. Such compounds often consist of long chain alkyl groups with attached polyoxyalkylene chains; the fatty acid or fatty alcohol residues providing lubricity as a consequence of their structural similarity to mineral lubricating oils and the polyoxyalkylene residues providing wetting of the fiber surface and water solubility. It is known to obtain lubricants derived from the oxyalkylation of diols, monols and fatty acids by utilizing a heteric mixture of oxyethylene and oxypropylene groups in the molecule of the fiber lubricant in accordance with U.S. Pat. No. 2,457,139 and U.S. Pat. No. 2,425,755. It is also known to produce lubricants for multi-filament polyester yarns by the heteric oxyalkylation of an initiator compound using ethylene oxide and 1,2-propylene oxide wherein said initiator is a fatty acid having 6 to 18 carbon atoms in the alkyl chain. Similar fiber lubricating compositions are disclosed in British Pat. No. 1,460,960 wherein fiber lubricants are produced by the heteric oxyalkylation of a fatty acid having 7 to 21 carbon atoms in the alkyl chain.